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About This Book

Welcome from Cress

Welcome, growers!

Cress the tree frog waving welcome Hi there — I'm Cress, your guide through everything roots, water, and nutrients. Whether you're starting with a single mason jar on a windowsill or dreaming up a multi-tier vertical farm, this book has been built to grow with you. Each chapter is paired with hands-on MicroSims you can poke, prod, and break — that's how the science sticks. Let's grow something amazing!

Why This Intelligent Textbook

Hydroponics sits at the intersection of biology, chemistry, engineering, food science, and data science — and the world needs students fluent in all five at once. Climate stress, urban food deserts, and agricultural water scarcity are converging just as inexpensive sensors, LEDs, and microcontrollers are bringing precision growing within reach of any classroom. The next generation of farmers will not look like the last, and the curriculum that prepares them must be built differently.

In the United States (2024–2025):

  • The U.S. Bureau of Labor Statistics projects employment of agricultural and food scientists to grow about 8% from 2023 to 2033, faster than the average for all occupations, with roughly 3,800 openings each year on average1.
  • USDA reports that agriculture, food, and related industries contributed about $1.5 trillion to U.S. GDP in 2023 — roughly 5.5% of the entire economy2.
  • According to NCES, fewer than half of U.S. 8th-graders scored proficient or above in science on the most recent NAEP assessment, underscoring the gap between economic demand and educational preparation3.

Worldwide:

  • The UN Food and Agriculture Organization reports that agriculture accounts for roughly 72% of all freshwater withdrawals globally — the single largest pressure on the planet's water supply4.
  • The United Nations projects the world population will reach about 9.7 billion by 2050, requiring a roughly 50% increase in food production over 2012 levels5.
  • Hydroponic systems can use as little as 10% of the water required by conventional field agriculture for the same crop yield, per peer- reviewed comparisons of resource efficiency in controlled-environment agriculture6.

These numbers are not abstract. They describe the kitchens your students will cook in, the careers they will compete for, and the planet they will inherit. Hydroponics is one of the few topics where a curious fifteen-year-old can build something real in a weekend that demonstrates a principle being used to feed cities.

This book takes a fundamentally different approach to the subject. It is built on a learning graph of 500 interconnected concepts organized so that each chapter introduces only what the previous chapter has prepared the student for — no jumping ahead, no orphan vocabulary. Throughout the book you will find 30 interactive MicroSims — browser-based simulations that let students manipulate nutrient solutions, tune VPD, model financial returns of a vertical farm, and diagnose nutrient deficiencies through direct experimentation rather than memorization. The entire textbook is open source and free — no paywalls, no access codes, no expensive annual editions, and every diagram, chart, and simulation can be remixed under a Creative Commons license.

How to Use This Book

This textbook is designed for self-paced study and classroom use. Each chapter builds on previous material, so reading in order is recommended. The book includes:

  • 21 Chapters covering plant physiology, nutrient chemistry, system design, lighting and environmental control, MicroPython and sensor hardware, IoT and data visualization, food safety, solar energy, vertical farming, and financial modeling
  • 30 Interactive MicroSims embedded in chapters — browser-based simulations you can manipulate to explore concepts (root anatomy, Mulder's chart, VPD dashboard, PPFD/DLI calculator, financial models, and more)
  • Chapter Quizzes at the end of each chapter to test understanding
  • Annotated References linking to Wikipedia and authoritative sources
  • Glossary with precise definitions for every key concept
  • Learning Graph visualizing how 500 concepts connect across chapters
  • Search available from any page using the search bar (top right)

The Learning Graph visualizes how concepts connect across chapters. If you want to explore non-linearly or check prerequisites for a specific topic, start there.

About the Author

Dan McCreary headshot

Dan McCreary is a semi-retired AI researcher, solution architect, and educator who has spent more than three decades helping Fortune 100 organizations reason over massive datasets. At Optum he founded the Generative AI Center of Excellence and led the team that built one of the world's largest healthcare knowledge graphs — spanning over 25 billion vertices — to unify member, provider, and patient insights. Dan's deep background in knowledge representation and systems thinking underpins the precise learning graphs and intelligent textbook workflows used throughout this course.

He is the co-author of Making Sense of NoSQL (Manning Publications), the founding chair of the NoSQL Now! conference, and a frequent keynote speaker on semantic search, ontology strategy, and AI hardware. Beyond industry, Dan has mentored students as a STEM volunteer since 2014 and now applies the same rigor to building open educational resources. You can visit the Intelligent Textbooks Case Studies to see over 87 textbooks that Dan has created or co-created with other authors.

Selected Credentials

  • B.A. in Physics and Computer Science from Carleton College
  • M.S.E.E. from the University of Minnesota
  • MBA coursework at the University of St. Thomas
  • Patent holder in semantic search and ontology management techniques
  • Advocate for large-scale Enterprise Knowledge Graph adoption across healthcare and education
  • Long-time promoter of accessible, low-cost AI-powered learning experiences

How to Cite This Book

If you reference this textbook in academic work, curriculum proposals, lesson plans, or other publications, please use one of the following citation formats.

APA (7th edition)

McCreary, D. (2026). Hydroponics: From Mason Jar to Vertical Farm. https://dmccreary.github.io/hydroponics/

Chicago (17th edition)

McCreary, Dan. 2026. Hydroponics: From Mason Jar to Vertical Farm. https://dmccreary.github.io/hydroponics/.

MLA (9th edition)

McCreary, Dan. Hydroponics: From Mason Jar to Vertical Farm. 2026, dmccreary.github.io/hydroponics/.

BibTeX

@book{mccreary2026hydroponics,
  title     = {Hydroponics: From Mason Jar to Vertical Farm},
  author    = {McCreary, Dan},
  year      = {2026},
  url       = {https://dmccreary.github.io/hydroponics/},
  note      = {Interactive intelligent textbook}
}

To cite a specific chapter, append the chapter number and title — for example:

McCreary, D. (2026). Chapter 1: Introduction. In Hydroponics: From Mason Jar to Vertical Farm. https://dmccreary.github.io/hydroponics/chapters/01-introduction/

License

This work is released under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License (CC BY-NC-SA 4.0). You are free to share and adapt the material for non-commercial purposes as long as you give appropriate credit and share your adaptations under the same license.

References

  1. U.S. Bureau of Labor Statistics. (2024). Agricultural and Food Scientists — Occupational Outlook Handbook. https://www.bls.gov/ooh/life-physical-and-social-science/agricultural-and-food-scientists.htm ↩

  2. U.S. Department of Agriculture, Economic Research Service. (2024). Ag and Food Sectors and the Economy. https://www.ers.usda.gov/data-products/ag-and-food-statistics-charting-the-essentials/ag-and-food-sectors-and-the-economy/ ↩

  3. National Center for Education Statistics. (2023). NAEP Science Assessment Results. https://nces.ed.gov/nationsreportcard/science/ ↩

  4. Food and Agriculture Organization of the United Nations. (2023). AQUASTAT — Water Use in Agriculture. https://www.fao.org/aquastat/en/overview/methodology/water-use ↩

  5. United Nations Department of Economic and Social Affairs. (2022). World Population Prospects 2022. https://population.un.org/wpp/ ↩

  6. Barbosa, G. L., et al. (2015). Comparison of Land, Water, and Energy Requirements of Lettuce Grown Using Hydroponic vs. Conventional Agricultural Methods. International Journal of Environmental Research and Public Health, 12(6), 6879–6891. https://doi.org/10.3390/ijerph120606879 ↩